The present invention relates to monitoring systems that are used for the detection, identification, control or location of events and items such as the passage or presence of a merchandise tag or an employee identification badge tag, a conveyor belt with baggage having a tag, or a cart equipped with a license plate style tag in a hallway, and specifically relates to antenna systems forming a part of such monitoring systems.
The utilization of monitoring systems such as tag systems that are designed for a specific purpose and application, such as the detection of a merchandise tag passing through a designated space adjacent to an exit, are well known. These systems typically incorporate discreet hardware architecture using analog techniques operating through the utilization of transmit and receive antennas positioned in close proximity to the control electronics operating the antennas. These systems are designed for the detection of a single type of event, such as the detection of a merchandise tag entering a designated area and are directed to a particular application having a predetermined surveillance area (e.g., adjacent an exit) for the detection of predetermined items (e.g., merchandise tags), and using a specific merchandise tag detection technique (e.g., frequency detection), and further using analog circuits and analog techniques for signal manipulation to provide an indication of the occurrence of the event. These specific designs, represent fixed configurations of systems for utilization with a particular application and are generally customized to fit that application. Antennas used in such prior art monitoring systems are typically pedestal type antenna positioned on either side of a doorway and are driven with conventional RF drivers to project an RF field through which an individual passes when entering the doorway. While there are many types of tags that are used in such prior art systems, one such type of tag is attached to merchandise and incorporates a resonant circuit connected to an antenna. Receipt of the RF field emanating from the pedestal antenna causes the tag circuit to oscillate and transmit a signal.
It is an object of the present invention to provide an antenna system for use in a monitoring system to facilitate the transmission and receipt of signals to and from a tag.
It is another object of the present invention to provide a high gain, differentially driven magnetic induction antenna for use in a monitoring system for the detection of a tag.
It is still another object of the present invention to provide an antenna that is digitally controlled and is both a transmit and a receive antenna.
It is still another object of the present invention to provide an antenna having a configuration to permit an individual to pass through the antenna while transporting a tag.
It is another object of the present invention to provide an antenna that permits the tracking of a tag in a two or three dimensional field to thereby permit the determination of tag position within the antenna""s field.
It is another object of the present invention to provide an antenna system in a monitoring system wherein the antenna exhibits a high Q during a transmitting mode and a lower Q during a receiving mode.
It is still another object of the present invention to provide an antenna system wherein an antenna is driven at a frequency of a resonant circuit and wherein the resonant circuit is squelched to prevent ringing of the circuit and permit the antenna to receive.
These and other objects of the present invention will become apparent to those skilled in the art as the description thereof proceeds.
The present invention is an antenna system for use in an integrated monitoring system having multiple configurations that are selected under program control. A host computer dynamically provides commands and inputs selecting the particular configuration and scenario of operation that the system is to assume for particular tasks and applications. The system includes a system controller that responds to the configuration request from the host computer, or operates on internal programs and commands, and in turn communicates over a serial bus with distributed and remote antenna taps and/or other data input and output ports. The antenna taps include a tap controller that sends and receives commands and data from and to the system controller to actuate the antenna system for transmitting and receiving selected signals and for communicating received signals to the system controller for converting the signals to digital format, putting the results in a storage and into a digital signal processing system for correlation, scanning and other operations. The system may, under program control, be configured to detect and control tags and associated items or events as well as other data inputs and outputs through ports connected to the system controller or bus such as door openings, alarms, camera images, bar code readings and the like. The antennas are each driven and controlled by a respective antenna tap that provides differential driving and tuning for that antenna.